Detection and Outcomes in Metastatic Invasive Lobular Breast Cancer Through Novel F-18 FAP PET

April 27, 2026 updated by: Randy Yeh

Improving Detection and Outcomes in Patients With Metastatic Invasive Lobular Breast Cancer Through Novel F-18 FAPI PET Imaging

This study is a pilot clinical imaging trial of a prospective, head-to-head comparison of 18F-Fibroblast Activation Protein Inhibitor (FAPI)-74 PET/CT versus standard-of-care 18F-Fluorodeoxyglucose (FDG) PET/CT in 15 patients with metastatic invasive lobular breast cancer (ILC). Patients will undergo both 18F-FDG PET/CT and 18F-FAPI-74 PET/CT within a 2-week period (14 days + 7 days) to compare lesions, tumor detection rates, and PET lesion intensity, as well as to assess the clinical value of the PET scans from the treating physician's and the patient's perspective.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Provision of signed and dated informed consent form
  • Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study
  • Females; Age > 18 years of age
  • Diagnosis of invasive lobular breast cancer, with pathologically confirmed metastatic disease.
  • ECOG performance status 0-2
  • No planned change in anticancer therapy between FDG and FAPI PET scans

Exclusion Criteria:

  • Patients who are pregnant or lactating
  • Patients who cannot undergo PET/CT scanning
  • Patients with total serum bilirubin or serum creatinine > 1.5 times the upper limit of normal

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: 18F-FAPI-74 PET/CT and 18F-FDG PET/CT
Study participants will undergo both standard-of-care whole body 18F-FDG PET/CT scan and investigational whole-body scan 18F-FAPI-74 PET/CT.
Drug: 18F-FAPI-74
FAPI scans will be performed as hybrid PET/CT examinations for attenuation correction and lesion localization. Each patient will be injected intravenously with 7 mCi +/- 2 mCi of 18F-FAPI-74 followed by a 20-minute (+/-10 min) uptake period.
Drug: 18F-FDG
FDG PET/CT will be performed per standard-of-care protocol at Mount Sinai Hospital. Patients will fast for at least 6 hours before FDG administration and plasma glucose levels will be checked to ensure < 200 mg/dL. Each patient will be injected intravenously with 15 mCi +/- 20% of 18F-FDG.
Procedure: PET/CT
FAPI PET/CT images will be acquired from the top of skull to mid-thigh. FDG PET/CT images will be acquired from the skull base to mid-thigh after a 60-min uptake period. Outside FDG PET/CT performed at another institutional can be accepted, if image quality and acquisition is comparable to standard-of-care protocol at Mount Sinai Hospital.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Proportion of lesions detected by 18F-FAPI-74 PET/CT
Time Frame: End of study, at 1 month
Proportion of lesions detected by 18F-FAPI-74 PET/CT but not by 18F-FDG PET/CT. All lesions will be mapped across both imaging modalities to determine whether they were detected by FAPI PET/CT but not by FDG PET/CT.
End of study, at 1 month

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Proportion of lesions detected by 18F-FDG PET/CT but not by 18F-FAPI-74 PET/CT
Time Frame: End of study, at 1 month
All lesions will be mapped across both imaging modalities to determine whether they were detected by FDG PET/CT but not by FAPI PET/CT.
End of study, at 1 month
Proportion of concordant lesions detected by both 18F-FAPI-74 PET/CT and 18F-FDG PET/CT
Time Frame: End of study, at 1 month
All lesions will be mapped across both imaging modalities to determine whether they were detected by both FAPI PET/CT and FDG PET/CT (i.e., concordant detection).
End of study, at 1 month
Tumor detection rate
Time Frame: End of study, at 1 month
Tumor detection rate, defined as the proportion (%) of patients with >1 lesion on 18F-FAPI-74 PET/CT compared to 18F-FDG PET/CT
End of study, at 1 month
SUVmax of the hottest lesion (lesion with highest SUVmax) on 18F-FAPI-74 PET/CT compared to 18F-FDG PET/CT and mean SUVmax across all lesions
Time Frame: End of study, at 1 month

SUVmax of each lesion identified on both 18F-FAPI-74 PET/CT and 18F-FDG PET/CT.

Two summary metrics will be derived per patient per modality:

Hottest lesion SUVmax: Defined as the highest SUVmax value among all detected lesions per patient per modality.

Overall SUVmax: model lesion-level SUVmax values
End of study, at 1 month
Tumor-to-background ratio (TBR)
Time Frame: End of study, at 1 month
Tumor-to-Background Ratio (TBR) will be defined as the SUVmax of the hottest lesion divided by the SUVmax of two background regions: the liver and the aortic blood pool.
End of study, at 1 month
Number of participants with change in therapeutic management decisions
Time Frame: End of study, at 1 month

Number of participants with change in therapeutic management decisions following review of 18F-FAPI-74 PET/CT compared to decisions based on 18F-FDG PET/CT alone

For each patient, an initial therapeutic management plan will be recorded based on findings from the 18F-FDG PET/CT scan alone. After the subsequent review of the 18F-FAPI-74 PET/CT scan, a revised management plan will be documented, reflecting any changes informed by the additional imaging data.
End of study, at 1 month
Change in disease status assessment
Time Frame: End of study, at 1 month
Change in disease status assessment (responding, stable, progressing) by treating physicians following review of 18F-FAPI-74 PET/CT compared to assessment based on 18F-FDG PET/CT alone Treating physicians will assign a disease status classification (responding, stable, or progressing) based on available clinical and imaging data from 18F-FDG PET/CT and then after reviewing the 18F-FAPI-74 PET/CT scan. We will summarize the distribution of disease status before and after the FAPI scan, along with the number and percentages of patients whose disease status assessment changed following the FAPI scan, along with the specific nature of those changes.
End of study, at 1 month

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Randy Yeh

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
The Society of Nuclear Medicine and Molecular Imaging

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Randy Yeh, MD, Icahn School of Medicine at Mount Sinai

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 30, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 11, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 11, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 16, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 1, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 27, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • STUDY-25-00364
  • PRMC-25-041 (Other Identifier: Icahn School of Medicine at Mount Sinai)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The completed dataset is the sole property of the Sponsor-Investigator's institution and should not be exported to third parties, except for authorized representatives of appropriate Health/Regulatory Authorities, without permission from the Sponsor-investigator and their institution.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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